JP2002274396A - Rack and pinion steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To press a rack in the direction of a meshed part with a pinion and prevent a member from being interfered with rack teeth without inducing complication and upsizing of a device. SOLUTION: A generally annular elastic member 12 having a pressing projection 13 swelling to an inner surface side is fixedly press-fitted to the inner surface of a cylindrical rack housing 7 so that the pressing projection 13 is allowed to abut on the rear surface side of a rack tooth forming part on the rack 3. Since the elastic member 12 is a simple unit part, a device structure can be simplified. Since the elastic member 12 is installed on the inner surface of the cylindrical rack housing 7, the diameter of the rack housing 7 can be reduced. Since the pressing projection 13 of the elastic member 12 is not disposed on the rack tooth 8 side, the interference of the rack teeth 8 with the elastic member 12 can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack and pinion type steering device, and more particularly to a steering device having an improved structure for preventing rattling of a meshing portion between a rack and a pinion.

[0002]

2. Description of the Related Art As a rack-and-pinion type steering apparatus, there is one disclosed in Japanese Utility Model Laid-Open Publication No. 7-15467.

In this device, a concave housing space is provided in a rack housing surrounding the rack so as to intersect with the direction in which the rack extends, and a pressing space which slides on the back side of the rack tooth forming portion on the rack is provided in this space. A member and a spring for urging the pressing member in the rack direction are arranged. In this device, urging means for pressing the rack in the direction of the meshing portion with the pinion is constituted by the pressing member and the spring, and the function of the urging means absorbs the processing tolerance of the rack or the pinion, and the function of the meshing portion is improved. It is designed to prevent rattling.

However, in this steering device, since the structure of the urging means is complicated, there is a problem that the entire device becomes large and the manufacturing cost increases. To cope with this, conventionally, for example, those disclosed in JP-A-7-323849 and 9-2
There is one disclosed in Japanese Patent No. 77944.

In the former, a bottomed cylindrical rack guide body having a concave surface at the top for sliding contact with the rack is formed by a plate member having elasticity, and provided on a rack housing so as to intersect with the extending direction of the rack. The rack guide body is accommodated in the provided accommodation space together with the reinforcing member, and the rack guide body and the reinforcing member constitute urging means.

In the latter, a cylindrical support member having an eccentric inner peripheral surface is mounted on a cylindrical inner surface of a rack housing, and a substantially cylindrical elastic holding member having elasticity in a radial direction is provided on the inner surface of the support member. A member is accommodated, the rack is slidably held by the elastic holding member, and a biasing means is constituted by the supporting member and the elastic holding member.
In this device, although the elastic holding member makes elastic contact with the rack from all circumferential directions, the inner circumferential surface of the support member supporting the elastic holding member is eccentric with respect to the inner surface of the rack housing. The function presses the rack in the direction of the meshing portion with the pinion.

[0007]

However, in the former steering apparatus, although the structure is slightly simplified, the rack main body and the reinforcing member constituting the urging means are accommodated in the radial direction of the rack housing. Since the rack housing must be arranged in a space, the rack housing expands in the radial direction in order to secure a storage space, and the outer shape of the rack housing becomes large.

On the other hand, in the latter steering device, since the supporting member constituting the urging means is attached to the cylindrical inner surface of the rack housing, it is possible to avoid an increase in the outer size of the rack housing. Since the member elastically contacts the rack from all circumferential directions, the edge portions on both sides in the width direction of the rack teeth formed on the rack come into contact with the elastic holding member, and the elastic holding member is likely to be quickly worn.

Therefore, the present invention provides an urging means for pressing the rack in the direction of the meshing portion with the pinion so that the urging means can be arranged without complicating or increasing the size of the device and without interfering with the rack teeth. Another object of the present invention is to provide a rack-and-pinion type steering device capable of reducing manufacturing costs and reducing the size of the device, as well as improving the durability of parts.

[0010]

As a means for solving the above-mentioned problems, the present invention provides a pinion to which a steering torque is input from a steering wheel, and a pinion meshed with the pinion to change the rotational torque of the pinion to the steering wheel. In a rack-and-pinion type steering apparatus, comprising: a rack that converts a forward-backward movement in a vehicle width direction to be steered; and a biasing unit that presses the rack toward a meshing portion with a pinion.
A substantially annular elastic member provided with a pressing protrusion swelling on the inner surface side only on substantially half of the circumferential direction is provided. The pressing protrusion is provided on the cylindrical inner surface of the rack housing surrounding the rack. The elastic member is attached so as to contact the rear side of the rack tooth forming portion on the rack, and the elastic member constitutes the urging means.

In the case of the present invention, the pressing protrusion of the elastic member attached to the inner surface of the housing presses the rear side of the rack tooth forming portion of the rack, thereby suppressing the rattling between the rack and the pinion. Further, since the pressing protrusion of the elastic member is not arranged on the movement path of the rack teeth, no interference occurs between the rack teeth and the elastic member.

Further, the elastic member may be attached to the inner surface of the rack housing by press fitting. In this case, since the diameter of the elastic member is reduced by press fitting, the pressing force of the rack by the pressing protrusion is increased.

Further, the pressing projection may be formed to have the same cross-sectional shape over the entire area in the axial direction of the elastic member, and the pressing protrusion may be formed to have an arc-shaped cross-sectional shape.

When a plurality of pressing protrusions are provided on the elastic member, it is preferable that the pressing protrusions are arranged symmetrically with respect to a line connecting the axis of the rack and the center of the width of the rack teeth. In this case, the urging force of the pressing projection acts not only in the direction in which the rack is pressed against the pinion, but also acts to suppress the rattling of the rack in the pinion axis direction.

It is preferable that the elastic member is disposed outside the position of the pinion in the rack housing in the vehicle width direction. In this case, the pressing position of the rack by the elastic member is closer to the end of the rack, and the rack is mounted on the vehicle. It is difficult to be cantilevered when displaced in the width direction.

Further, a step may be provided on the inner surface of the rack housing, where the end surface of the elastic member abuts. In this case, the axial position of the ring member is positioned by the step when the elastic member is attached. You.

[0017]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG.

In the drawings, 1 is a rack and pinion type steering device according to the present invention, and 2 is
A pinion shaft 3 to which a steering force is input from a steering wheel (not shown) meshes with a pinion 4 of the pinion shaft 2 and converts the rotational torque of the shaft 2 into a forward / backward movement in the vehicle width direction to steer the steered wheels. The rack 5 is connected to an end of the rack 3 via a ball joint 6, and transmits a side rod for transmitting the operation of the rack 3 to steered wheels.
Reference numeral 7 denotes a substantially cylindrical rack housing which is fixedly installed on the vehicle body along the vehicle width direction and surrounds the peripheral area of the rack 3.

On the side surface (upper surface in FIG. 1) of the rack 3, rack teeth 8 meshed with the pinion 4 are formed along the longitudinal direction. As shown in FIGS. 2 and 3, the rack teeth 8 are formed so that a part of the circular cross section of the rack 3 is notched.

A pinion accommodating portion 9 for accommodating the pinion 4 is integrally formed at a position deviated to one of the left and right sides in the vehicle width direction of the rack housing 7. A large-diameter portion 10 whose inner diameter is larger than the inner surface of the general portion is provided at a position on the inner surface of the cylindrical portion of the rack housing 7 near the pinion housing portion 9 on the outer side in the vehicle width direction. A step portion 11 is provided between the large diameter portion 10 and the general portion. An elastic member 12 is attached to the large-diameter portion 10 of the rack housing 7 as urging means for pressing the rack 3 in the direction of the meshing portion with the pinion 4.

As shown in FIG. 4, the elastic member 12 is formed in a substantially cylindrical shape by a resin or the like, and a part of the cylindrical cross section has a pair of pressing members bulging in an arc shape toward the inner surface. Protrusions 13, 13 are formed. These pressing projections 1
The protrusions 3 and 13 are formed in the same cross-sectional shape over the entire region of the elastic member 12 in the axial direction, and the protrusions 13 and 13 are arranged closer to one half of the elastic member 12 in the circumferential direction.

The elastic member 12 is press-fitted and fixed to the large-diameter portion 10 of the rack housing 7 so that one end surface of the elastic member 12 comes into contact with the step portion 11 so as to be positioned in the axial direction. As shown, the pair of pressing projections 13 abut on the rear side of the rack tooth forming portion of the rack 3,
Is adjusted so as to elastically press the pinion 4 in the direction of the pinion 4. The orientation of the elastic member 12 at this time is more strictly symmetrical with respect to a line p connecting the axis o of the rack 3 and the width center c of the rack teeth 8 with both pressing projections 13, 13. The rack 3 is in contact with the rack 3 at a certain position.

Since the steering device 1 is configured as described above, the rack 3 is provided with the pressing protrusion 1 of the elastic member 12.
The rack 3 and the pinion 4 are pressed by the pressers 3 and 13 in the direction of the meshing portion with the pinion 4, and the processing tolerance of the rack 3 and the pinion 4 is absorbed by the pressing. As a result, the rack 3 and the pinion 4 always mesh without rattling, and the rotational torque of the pinion 4 is smoothly transmitted to the rack 3.

The elastic member 12 that presses the rack 3 in the direction of the meshing portion has a pressing protrusion 13 formed only in a region of the rack 3 in contact with the rear side of the rack tooth forming portion. The pressing projections 13 are not arranged on the movement path of the rack teeth 8, so that the edge portions on both sides in the width direction of the rack teeth 8 do not contact the elastic member 12. Therefore, the elastic member 12 is unlikely to suffer deterioration such as wear. Further, since the elastic member 12 is a single ring-shaped component having a simple structure, the manufacturing cost can be reduced. Further, since the elastic member 12 is attached to the cylindrical inner surface of the rack housing 7, the rack housing 7 is almost completely mounted. There is no need to increase the size in the radial direction.

The elastic member 12 is connected to the rack housing 7.
When the rack 3 is pressed into the large-diameter portion 10, the pressing protrusion 13 is pressed to the inner surface side with the reduction in diameter, so that the pressing force of the pressing protrusion 13 on the rack 3 is higher than at this time. In particular, in the case of this embodiment, since the pressing projection 13 is formed in the same cross-sectional shape over the entire area in the axial direction, the top of the pressing projection 13 is largely raised by the diameter reduction of the elastic member 12 due to the press-fitting. By pushing up, a greater pressing force increasing effect can be obtained. When the elastic member 12 is formed to have the same cross-sectional shape over the entire area in the axial direction as in this embodiment, there is an advantage that the formed elastic member 12 can be easily removed from the mold. .

Further, since the pressing projection 13 is formed in an arc-shaped cross section and comes into contact with the rack 3 by a line, the pressing projection 13 does not hit the rack 3 in one side, and has a play at the contact portion. The problem of sticking does not occur. Also,
In the case of this embodiment, since the pair of pressing projections 13 are arranged symmetrically with respect to a line segment p substantially perpendicular to the tooth surface of the rack 3, the racks 3 are pinched by the pressing projections 13. Not only can be pressed in the direction of the meshing portion with the pinion 4, but also the fluctuation of the rack 3 along the axial direction of the pinion 4 (the left-right direction in FIG. 3) can be controlled at the same time.

The elastic member 12 may be arranged either outside or inside in the vehicle width direction across the pinion housing 9 in the cylindrical portion of the rack housing 7, but as in this embodiment. When the rack 3 is disposed outside in the vehicle width direction, even if one end of the rack 3 is largely displaced outward in the vehicle width direction, it is difficult to support the rack 3 and the operation of the rack 3 can be stabilized.

Although the embodiment in which the elastic member is formed of a resin has been described above, the elastic member is not limited to the resin but may be a thin plate-shaped metal or the like which can be elastically deformed. Further, the elastic member for urging the rack does not need to be a complete annular shape as in the above-described embodiment.For example, a cut for pushing open a part of the circumference so as to be annular in the mounted state. It may be formed, or may be formed completely in a substantially C-shaped cross section.

[0029]

As described above, according to the present invention, the urging means for pressing the rack in the direction of the meshing portion with the pinion is constituted by a substantially annular elastic member having a pressing projection, and the elastic member is formed of the housing. Since the apparatus is mounted on the cylindrical inner surface, the apparatus can be simplified and downsized. Further, the pressing protrusion of the elastic member is not arranged on the movement path of the rack teeth so that the rack teeth and the elastic member Since the interference is eliminated, it is possible to avoid a decrease in the durability of the component due to abrasion or the like.

When the elastic member is mounted on the inner surface of the rack housing by press-fitting, the pressing force of the rack by the pressing projections is increased by reducing the diameter of the elastic member at the time of press-fitting, so that there is a play between the rack and the pinion. Sticking can be more reliably suppressed.

Further, when the pressing projection is formed in the same cross-sectional shape over the entire area in the axial direction of the elastic member, the mold can be easily removed at the time of molding, so that the production at lower cost can be realized. . In this case, when the elastic member is further press-fitted into the rack housing, the entire pressing protrusion bulges more in the rack direction due to the reduced diameter of the elastic member.
The pressing force against the rack can be further increased.

Further, in the case where the cross section of the pressing projection is formed in an arc shape, the pressing projection can be brought into contact with the rack at a line or a point to eliminate one-side contact and prevent rattling at the contact portion. it can.

When a plurality of pressing protrusions are arranged on the elastic member so as to be symmetrical with respect to a line connecting the axis of the rack and the center of the width of the rack teeth, the pressing protrusions may be used in the pinion axial direction. The rattling of the rack can be suppressed at the same time.

When the elastic member is disposed outside the position of the pinion in the rack housing in the vehicle width direction, the rack is less likely to be cantilevered due to the displacement of the rack in the vehicle width direction. Thus, it is possible to always press stably.

Further, on the inner surface of the rack housing,
In the case where a step portion with which the end surface of the elastic member abuts is provided, the elastic member can be reliably positioned in the axial direction by the step portion.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the same embodiment, taken along line AA of FIG. 1;

FIG. 3 is an exemplary sectional view of the embodiment, taken along line BB of FIG. 1;

FIG. 4 is an exemplary perspective view of an elastic member showing the embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Steering device 3 ... Rack 4 ... Pinion 7 ... Rack housing 11 ... Step part 12 ... Elastic member (biasing means) 13 ... Pressing protrusion

Claims (7)

[Claims] 1. A pinion to which a steering torque is input from a steering wheel, a rack that meshes with the pinion, and converts a rotational torque of the pinion into a forward / backward movement in a vehicle width direction to steer a steered wheel. And a biasing means for pressing toward the meshing portion of the rack-and-pinion type steering device, wherein a substantially annular elastic member provided with a pressing protrusion bulging inward only on substantially a half side in the circumferential direction. The elastic member is attached to a cylindrical inner surface of a rack housing surrounding the rack such that the pressing protrusion abuts on the rear side of the rack tooth forming portion on the rack, and the urging means is provided by the elastic member. And a rack and pinion type steering device. 2. The rack-and-pinion steering apparatus according to claim 1, wherein said elastic member is attached to an inner surface of a rack housing by press-fitting. 3. The rack-and-pinion steering device according to claim 1, wherein the pressing projection is formed to have the same cross-sectional shape over the entire area of the elastic member in the axial direction. 4. The rack-and-pinion steering apparatus according to claim 1, wherein said pressing projection is formed in an arc-shaped cross section. 5. A plurality of pressing projections are arranged on an elastic member so as to be symmetrical with respect to a line connecting the axis of the rack and the center of the width of the rack teeth.
4. The rack and pinion type steering device according to item 1. 6. The rack-and-pinion steering apparatus according to claim 1, wherein the elastic member is disposed outside the position of the pinion in the rack housing in the vehicle width direction. 7. The rack-and-pinion type steering device according to claim 1, wherein a step portion with which an end surface of the elastic member abuts is provided on an inner surface of the rack housing.